1. Field of the Invention
The present invention relates to a development system constituted by toner, a toner carrier, a toner supply member and a toner layer thickness regulating member. More particularly, it relates to the relationship in the order between respective triboelectric series a toner carrier, a toner base particle and a surface additives.
2. Conventional Art
As electronic photography, heretofore, a large number of methods based on the Carlson's process disclosed in U.S. Pat. No. 2,297,691 have been proposed. In general, an electrostatic latent image is formed on a photosensitive material using a photoconductive substance. Then, fine powder called "toner" is selectively deposited on the latent image to perform development to thereby make the latent image visible. After toner for making the latent image visible is transferred to a transfer material such as paper or the like as occasion demands, the toner is fixed by heat and pressure or by solvent vapor to thus obtain a matter on which an image is formed.
Development methods of making the electrostatic latent image on the photosensitive material visible are roughly classified into dry developing methods and liquid developing methods. Among the dry developing methods, a magnetic brush developing method, a cascade developing method and so on are known as a two-component developing method using a carrier. Further, a jumping developing method, a FEED developing method, a magnetic brush developing method and so on are known as a one-component developing method. As toner for making the electrostatic latent image visible, negative toner or positive toner is used. As a development system, positive development and reversal development are used.
Particularly as a developing method in which toner is formed as a thin layer on a toner carrier by a regulating member, and the toner is conveyed to a latent image carrier to thereby make a latent image visible, various kinds of methods have been disclosed in Japanese Patent Postexamination Publication No. Sho-52-36414, Japanese Patent Unexamined Publication Nos. Sho-57-114163, Sho-54-43027 and Sho-55-18656, and so on. In these aforementioned developing methods, carrier particles as used in the two-component developing method are not used, so that electric charges must be given to toner efficiently by a toner carrier, a toner layer (thickness) regulating member and a supply member.
To solve this problem, heretofore, various proposals have been made. For example, in Japanese Patent Postexamination Publication No. Sho-51-36070, a doctor blade disposed far from toner with respect to triboelectric series is used. In Japanese Patent Postexamination Publication No. Hei-4-6953, a material of a non-magnetic sleeve disposed far from the triboelectric series of toner. In Japanese Patent Unexamined Publication No. Sho-60-45272, an electrification member provided under the consideration of a triboelectric series caused by friction against a developer is applied onto a carrier surface and a layer-regulating member.
In Japanese Patent Unexamined Publication No. Sho-61-39272, there is a proposal in which a fluidization assistant being enough near but free from triboelectric charge in the point of view of triboelectric series of the toner layer (thickness) regulating member is used. With respect to a surface additives provided in the surface portion of toner, use of silica is popularized to give fluidity to toner to thereby form a high-quality image. With respect to the surface additives, however, various proposals for improvement have been made. For example, in Japanese Patent Postexamination Publication No. Sho-54-16219, Japanese Patent Unexamined Publication Nos. Sho-55-159450 and Sho-61-277964 and so on, minus-charge toner obtained by hydrophobing silica with dimethyldichlorsilane, hexamethyldisilane and silicone oil is disclosed.
Further, in Japanese Patent Unexamined Publication No. Sho. 55-79454, a developing agent having a surface treated with organic acid having carbon fluoride groups in order to change the triboelectric series thereof to thereby prevent filming is disclosed. Further, in Japanese Patent Postexamination Publication Nos. Sho. 63-62740 and Hei. 4-145448, toner in which the state of deposition of the surface additives is limited is disclosed. There is however no improvement but an improvement in the relationship between the triboelectric series of toner carrier and toner, an improvement in surface treatment of the surface additives, and the like. Even in the case where the aforementioned methods are used, there arises a problem in that it is difficult to reduce deposition of toner onto a non-image portion, that is, it is difficult to reduce fogging in the ground. Further, the aforementioned methods are weak against the change of time and the change of environment. There arises a problem in that it is difficult to provide stably a high-quality image free from fogging in the ground. Causes of such problems, however, have been not made clear yet.